1. Field of the Invention
The present invention relates to a composite rupture disk assembly, and more particularly, to an improved composite rupture disk assembly of the type which includes a resilient sealing member and a rupture member.
2. Description of the Prior Art
A variety of safety pressure relief devices of the rupturable type have been developed and used heretofore. Commonly, such devices include a rupture member or disk which is of a particular strength whereby it ruptures when a predetermined fluid pressure is exerted thereon. The rupture disk is most often clamped between a pair of annular supporting members positioned in a pressure relief passageway or conduit connected to a pressure vessel or system being protected by the rupture disk.
While safety pressure relief devices comprised of a single rupture disk supported between supporting members are commonly utilized in particular applications, composite rupture disk assemblies comprised of two or more parts are also commonly used. A particular type of composite rupture disk assembly to which this invention relates is comprised of a metallic or other rigid material rupture member positioned adjacent a resilient sealing member. Such composite rupture disk assemblies are adapted to be clamped between annular supporting members, and often include several other parts in addition to the rupture member and resilient sealing member.
The rupture member includes openings formed therein whereby when fluid pressure is exerted on the sealing member, the sealing member is pressed against the rupture member and the fluid pressure is transmitted to the rupture member. When the pressure reaches a predetermined rupture pressure, i.e., the pressure at which the rupture member is designed to fail, rupture occurs whereby the rupture member as well as the sealing member tear open and fluid pressure is relieved through the annular supporting members.
In applications where reverse pressures can be encountered, e.g., a vacuum can be generated within the vessel or system being protected, a support member is provided which is positioned on the side of the resilient sealing member opposite the rupture member. When reverse pressure is applied to the composite assembly, the sealing member is pressed against the support member which either prevents the sealing member from rupturing, or the support member ruptures when the reverse pressure reaches a predetermined rupture pressure thereby relieving fluid pressure in the reverse direction.
Heretofore, the rupture member of the above-described type of composite rupture disk assembly has included a plurality of elongated openings formed therein, generally in the form of slits, which extend outwardly from a central portion towards the periphery of the rupture member. The slits have included enlarged circular holes at the inner and outer ends thereof, and the slits and holes have defined sector shapes in the rupture member. In order to control and predetermine the rupture pressure of the rupture member, the distance between the closest of the holes at the inner ends of adjacent slits and the thickness of the material from which the rupture member is formed have been varied. That is, a trial and error procedure has been employed whereby one or more rupture members of an initial material thickness with a particular hole distance are manufactured and tested. Depending upon the resultant rupture pressure of the initial rupture members, additional rupture members are produced and tested with changes in the hole distance and/or in the material thickness until the desired rupture pressure is obtained. A group of rupture members is then produced identical in material thickness and hole distance to the rupture member having the desired rupture pressure.
As is well understood by those skilled in the art, the trial and error procedure described above is tedious, timeconsuming and expensive. By the present invention an improved rupture member and composite rupture disk assembly including the rupture member are provided wherein the holes at the ends of the slits can optionally be eliminated and, more importantly, instead of controlling the rupture pressure by means of the distance between adjacent holes or the thickness of the material forming the rupture member, one or more scores are formed in the rupture member between at least two of the elongated openings formed therein. Such score or scores are easily formed in a rupture member, and allow a single thickness of material to be used for rupture members having a variety of predetermined rupture pressures as well as a more economical trial and error procedure to be followed and a more economical composite rupture disk assembly to be produced.